EM78P259N/260N

8-Bit Microprocessor with OTP ROM

6.12.3 Residual Voltage Protection

When the battery is replaced, device power (Vdd) is removed but the residual voltage remains. The residual voltage may trip below Vdd minimum, but not to zero. This condition may cause a poor power-on reset. Fig. 6-22 and Fig. 6-23 show how to create a protection circuit against residual voltage.

Vdd

Vdd

EM78P259N

33K

EM78P260N

 

Q1

10K

/RESET

 

100K

1N4684

 

Fig. 6-22 Residual Voltage Protection Circuit 1

Vdd

 

Vdd

EM78P259N

 

R1

EM78P260N

Q1

 

 

 

/RESET

 

 

 

R3

R2

Fig. 6-23 Residual Voltage Protection Circuit 2

66 •

Product Specification (V1.2) 05.18.2007

(This specification is subject to change without further notice)

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IBM EM78P259N/260N manual Residual Voltage Protection, Vdd, EM78P260N